On Fri, 21 Feb 2014 12:31:28 -0500, "Charlie" <
le...@thestation.com>
wrote:
>I have had this robotic floor sweeper for a half dozen years.
What's the exact model number? I've fixed a few of these and found
that each has its own idiosyncrasies.
>The original
>NiCad battery died and I replaced it with an aftermarket NiMh replacement
>that worked fine for several years.
Perhaps it would be helpful if you converted "several" into a number.
How many years did the NiMH battery last? More specifically,
approximately how many charge cycles? A really good NiMH battery will
last for about 1000 cycles if everything is done perfectly, or about
50 charge cycles if you do everything wrong. Much depends on the
detection of the EOC (end of charge) point in the charge controller.
If it's a dozen years old and was originally designed for a NiCd, it
is unlikely that the EOC algorithm is suitable for an NiMH battery.
You can easily overcharge the battery, with will kill an NiMH battery
rather quickly.
>The NiMh replacement is
>labeled 14.4 volts. My cheap VOM show about 14-15 volts. Seems good to me.
Test it under a load outside of the sweeper. Try to approximate the
operating current of the Roomba with a resistor. For more accurate
results, borrow a discharge tester such as a West Mtn Radio CBA:
<
http://www.westmountainradio.com/cba.php>
>I sent an email to the robot company asking for their take on the problem.
>Their response was that buying a new NiCad from them would solve the
>problem.
You can get a NiCd replacement cheaper on eBay or Amazon. If you're
not sure if the charger will work properly with an NiMH battery, then
perhaps reverting to a NiCd might not be such a bad idea.
>I am a skeptic.
I am a cynic.
>I think that customer service just has a checklist that is
>simple-minded and covers only what the average consumer can do.
In my experience, that covers at least 90% of the questions. Answers
like "is it plugged in?" are all too common. In the distant past, I
spent some time on a support phone pool creating a database of boiler
plate answers. I wasn't too happy with the software or my answers,
but it was a start and worked tolerably well.
>Along with the email response was a phone number if there was still a
>problem. I called and essentially got the same answer. I said that my
>concern is that a new battery will not solve the problem. I think that the
>voltage sensing circuit has failed.
The only way you're going to know if the voltage sensing or whatever
circuit has failed is to either buy or borrow a known working battery.
Troubleshooting by replacment is an old and quite effective method of
fixing things.
>I asked if there wasn't someone who
>understood the inner workings of this box who could shed light on what is
>happening. I was put on hold and then was told that there was nobody else to
>talk to.
I used to design marine radios. The dealers knew the engineers by
name and usually bypassed the normal support channels. They would
spread the broken radio onto the table, and then have me walk them
through the troubleshooting and repair. That saved them the cost of
hiring a qualified technician. That might explain why there was
nobody available with a clue.
>What was offered was a discount on the replacement and that if it did not
>solve the problem the replacement could be returned for a refund. I bit at
>that offer and we will see what happens.
I suspect a replacement battery would have been cheaper and faster.
>I am open to thoughts that there is a reason that the replacement battery is
>at fault.
You may have killed the NiMH with a charger made for a NiCd. Or, you
overcharged it with a charger that didn't have a suitable EOC circuit.
>If the fault is in the robot, it is doomed to the recycle bin.
<
http://www.ifixit.com/Manifesto>
>There is not likely to be anything that I can do without a service procedure
>for guidance. I also suspect there will be a control board with
>non-standard components that are unobtainable.
About half of my repairs are mechanical, not electrical. A sweeper
full of hair, dirt, and crud will bog the motor, causing the battery
to drain or die rather quickly. Add those that like to fix things
with far too much oil, which soon turns to tar. It's amazing how many
things can be fixed by simply cleaning out the crud.
Good luck.
--
Jeff Liebermann
je...@cruzio.com
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS
831-336-2558